The invention relates to the field of sports involving gliding over snow. It relates more particularly to the devices used on skis and, in particular, downhill skis. It refers more specifically to devices for raising bindings, making it possible to optimize the transmission of the bearing forces exerted by the skier toward the board.
In a known manner, boards for gliding and, in particular, downhill skis include safety bindings consisting of a stop which interacts with the toe of the boot and a heelpiece holding the rear of the boot.
It is well known to mount the binding elements on raising platforms, the aim of which is to elevate the boot above the board for gliding. This is particularly advantageous when the board for gliding has a relatively pronounced sidecut, and it is thus necessary to prevent the boot coming into contact with the snow when the board is inclined laterally.
Other raising platforms have already been proposed to provide a degree of unclamping of the ski. In this type of platform, the rigidity of the sole of the boot and that of the board are dissociated in such a manner that the behavior of the ski corresponds to the intrinsic properties of the board independent of that of the boot.
Other types of raising platform have also been proposed which, on the contrary, act as stiffener in order to increase further the rigidity and stiffness of the board, in particular in the underboot zone. One example of such a platform is, in particular, described in document FR 2 684 885, in which the various elements mounted on the platform interact with one another when a force is exerted vertically by the skier.
A further example of this type of platform is described in document U.S. Pat. No. 5,704,628. Such a platform includes an arm which makes it possible to transmit a portion of the forces exerted longitudinally by the skier as far as an advanced zone located beyond the stop. The arm is connected to a take-up piece secured to the board so that a longitudinal force is exerted on the ski between the stop and the take-up piece in order to give rise to a stiffening. Unfortunately, because of the articulation of the arm for transmitting forces, this type of device does not make it possible to exert vertical forces in front of or behind the elements of the binding.
Another type of platform has also been proposed, such as that described in document FR 2 777 792. Such a platform is composed of a raising plate on which the elements of the binding are arranged. This raising plate rests on flexible strips which extend to the front and to the rear of the zone for mounting the binding, and bear on the upper face of the ski by means of shock-absorbing blocks.
On account of the flexibility of the longitudinal tongues, such a device does not make it possible to transmit sufficiently effective bearing forces, in particular when the skier exerts forces at the location of one of the elements of the binding. Moreover, the presence of elastomeric blocks tends to damp the behavior of the board overall, so such devices are intended more for relatively soft skis and, conversely, very dynamic skis, in particular those used in competition.
A problem which the invention proposes to solve is allowing a raising platform to modify the behavior of the board for gliding when the forces are exerted by the skier, while not increasing its stiffness in terms of flexing and thus allowing it to bend.
The invention thus relates to a device for raising at least one binding element used on a board for gliding, including an element which is articulated relative to the board, one end of which comes into contact with the upper face of the board.
This device is defined in that the binding element is mounted on the articulated element and in that said end of the articulated element is secured to the upper face of the board by attaching means in such a manner that the forces exerted vertically at the location of the element of the binding are partly transmitted to the board at the location of said end of the articulated element.
In other words, the articulated element serves as a lever and directly receives the vertical bearing forces exerted by the skier. Via its end which is secured to the ski, this lever exerts a portion of these forces in a zone which is offset relative to the binding. These forces may be transferred in front of the stop of the binding or behind the heelpiece. Complementarily, the raising device according to the invention does not interfere with the behavior of the board when the latter bends, since the articulation of the articulated element allows the platform as a whole to deform when the board flexes.
Advantageously, in practice, the articulated element on which the element of the binding is mounted may be articulated either directly on the structure of the board or, alternatively, relative to a fixed element secured to the upper face of the board.
In this latter case, provision may be made for the fixed element to receive also the binding element which is not mounted on the articulated element, in such a manner that the entire binding is mounted on the same raising device.
Various modes of behavior may be obtained depending on the position of the point of articulation relative to the element of the binding.
Thus, in a first embodiment, the articulated element may be articulated relative to the board at the location of its end opposite the end secured to the upper face of the board, in such a manner that the forces exerted at the location of the element of the binding give rise, on the upper face of the board, to a force in the same direction.
In other words, the element of the binding is then between the articulation relative to the board and the end of the articulated element which rests on the board.
In this way, when the skier initiates a turn and exerts forces at the location of the front stop of the binding, a portion of these forces is exerted via the device according to the invention a few centimeters or even a few tens of centimeters in front of the stop. Under these conditions, the bearing forces are exerted in a longer zone of the underboot section, which allows efficient turn initiation and better control through the turn. This type of behavior is particularly sought-after in competitions of the giant-slalom type, in which turn initiation is particularly important.
Conversely, in a second embodiment, the articulated element may be articulated relative to the board at a location located between the site of the element of the binding and the end secured to the upper face of the board, in such a manner that the forces exerted at the location of the element of the binding give rise, on the upper face of the board, to a force in the opposite direction. In other words, the articulation of the articulated element is between the element of the binding and the point of attachment of the articulated element on the ski.
In this way, when the skier initiates a turn and exerts forces at the location of the stop of the binding, a portion of these forces is exerted via the device according to the invention in front of the stop, and they tend very slightly to raise the board in its front part or at the very least to shorten the zone of application of the pressure exerted by the ski on the snow. In this way, the bearing forces exerted by the skier tend slightly to bend the ski which then behaves as a board of shorter length.
It is thus easier and quicker to then link in the following turn.
It will be appreciated, therefore, that this type of behavior is particularly sought-after within the context of xe2x80x9cspecialxe2x80x9d slaloms, in which linking of the turns is particularly important.
Advantageously, in practice, the articulated element may include a transverse groove located on its upper face and sited between the site of the element of the binding and the end secured to the upper face of the board, said groove being filled with an elastic material so as to allow the flexing of said articulated element when the board flexes and its rapid return into position when the cause of the flexing has disappeared.
In other words, this groove allows a supplementary deformation of the raising device which is added to the articulation capability.
Moreover, the presence of an elastic material makes the raising device and thus the entire board more dynamic by opposing excess flexing of the articulated element. By using elastic materials which also possess shock-absorbing properties, such as viscoelastic materials, it is also possible to absorb a portion of the energy which has given rise to the deformation of the articulated element, by virtue of the shearing of the viscoelastic material. In this case, it is, in particular, possible to absorb a certain portion of the vibrations propagating along the board.
Advantageously, in practice, the means for attaching the end of the articulated element onto the upper face of the board allow a longitudinal displacement of said articulated element when the ski is significantly bent.
In other words, when the board is significantly bent, the end of the bearing zone may slide slightly relative to the upper face of the board in order to prevent longitudinal forces being exerted on the board. Indeed, the attaching means have the essential function of transferring a portion of the vertical forces exerted by the skier and must not secure the raising device via two ends, at the risk of generating clamping of the board.
Advantageously, in practice, this ability of the end of the articulated element to be displaced longitudinally may be obtained by interposing a layer of viscoelastic material between the upper face of the board and the end of the articulated element.
In this case, the layer of viscoelastic material efficiently transmits forces which are exerted vertically, and works in shear when the articulated element tends to be displaced longitudinally.
In practice, the lower face of the articulated element is shaped so as to clear an empty space between the articulated element and the upper face of the board, between the end secured to the board and the point of articulation of the articulated element.
In other words, only the end of the articulated element comes into contact with the board in order not to risk clamping the board and to push back as far as possible from the binding the zone in which the forces are transferred.
In a more improved embodiment, the device according to the invention may also include a second element which is articulated relative to the board, on which is mounted the other element of the binding and one end of which is secured to the upper face of the board by attaching means.
In this way, similar modes of behavior are obtained when forces are exerted at a location in front of or behind the binding.
In this case, advantageously, in practice, the two articulated elements may be articulated relative to the board about a common articulation pin.
As already stated, this articulation may be achieved either directly on the board or on a fixed element secured to the board.
In a particular embodiment, the two articulated elements may be mechanically secured to one another so as to form a rocker.
In this case, when the forces are exerted, for example, at the location of the front of the binding, the front of the board [lacuna] equally forces exerted downward, extending the zone over which the bearing forces are exerted, while the rear zone is eased and slightly bent.
Advantageously, in practice, the articulated element may include, on its lower face, in line with the site of the binding element, elastic return means.
These means may consist of a compressible foam which has the supplementary advantage of filling in a portion of the volume located under the articulated element in order to prevent the formation of accumulations of snow. These means may also be viscoelastic in order to afford the skier greater comfort.
In a particular embodiment, the articulated element may include two arms extending in the longitudinal direction of the board, these arms being connected at the location of the means for attaching to the board.
In this way, the transmission of forces in the vicinity of the lateral zones of the board, substantially in line with the edges, is promoted.